The use of pulmonary function tests (PFTs) has been widely described in airway diseases like asthma and cystic fibrosis, but for children's interstitial lung disease (chILD), which encompasses a broad spectrum of pathologies, the usefulness of PFTs is still undetermined, despite widespread use in adult interstitial lung disease. A literature review was initiated by the COST/Enter chILD working group aiming to describe published studies, to identify gaps in knowledge and to propose future research goals in regard to spirometry, whole-body plethysmography, infant and pre-school PFTs, measurement of diffusing capacity, multiple breath washout and cardiopulmonary exercise tests in chILD. The search revealed a limited number of papers published in the past three decades, of which the majority were descriptive and did not report pulmonary function as the main outcome.PFTs may be useful in different stages of management of children with suspected or confirmed chILD, but the chILD spectrum is diverse and includes a heterogeneous patient group in all ages. Research studies in well-defined patient cohorts are needed to establish which PFT and outcomes are most relevant for diagnosis, evaluation of disease severity and course, and monitoring individual conditions both for improvement in clinical care and as end-points in future randomised controlled trials.

Multiple breath washout test (MBW) with lung clearance index (LCI) as a main outcome parameter has proven to be a valuable research tool in patients with cystic fibrosis (CF) [1, 2]. Moreover, there is growing evidence of its relevance in routine clinical practice [3]. Nevertheless, some technical limitations remain that hamper its widespread use. While most of the MBW data in infants have been acquired via sulfur hexafluoride washout (SF 6-MBW), the nitrogen variant (N 2-MBW) is recommended by the European Cystic Fibrosis Society Clinical Trial Network (ECFS-CTN) for older children. However, this methodological discrepancy may limit long-term follow-up of cystic fibrosis patients because N 2and SF 6-MBW cannot be used interchangeably. In infants, the N 2-MBW has not been fully investigated to date. We report our data regarding safety, feasibility and repeatability of N 2-MBW in cystic fibrosis infants. Between January 2015 and January 2017, we performed lung function testing in 35 infants aged 6.7-25.2 months (median 14.7) with classical form of cystic fibrosis. Testing was performed in patients without any signs of acute respiratory infection for at least 14 days. Quiet sleep was induced by administering chloral hydrate 80-100 mg•kg −1 per rectum. The patients were placed in a supine position with their head and neck in a neutral position, and a Rendell-Baker face mask Nr. 1 or 2 (selected to keep the instrument dead space under 2 mL•kg −1) was tightly sealed around the mouth and nose. At first, N 2-MBW was performed using the Exhalyzer D device (Ecomedics, Duernten, Switzerland) with the Spiroware 3.2.0 software, following all the relevant recommendations [4, 5]. When finished, at least 120 s of medical air breathing followed (normalisation of breath pattern, nitrogen back wash-in). Afterwards, SF 6-MBW was performed using the same device and software within a subgroup of 10 patients, who were tested after March 2016 (SF 6-MBW became available in our centre); their anthropometric parameters and age were not significantly different from those of the whole study group. Both measurements were performed in fixed order within the same sedation period and without changing the body and face mask position. The technical acceptability of trials was assessed by a physician with ECFS-CTN certification in this method and adhered to the standard operating procedure for N 2-MBW [5] modified for infants and SF 6-MBW. Both tests were repeated at least three times to obtain a coefficient of variation (CV) lower than 10%. Pulse rate and haemoglobin oxygen saturation were continuously monitored during MBW measurements and until full consciousness was regained. A pair-wise t-test was used to compare results from SF 6and N 2-MBW in individual patients with both measurements available (n=8). Patient's characteristics between the N 2-MBW and SF 6-MBW group were compared by the t-test. The reliability of N 2-MBW was assessed using estimates of intraclass correlation (ICC). Coefficient of repeatability was calculated as follows: 1.96×...

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Detection of lung sounds and their propagation is a powerful tool for analysing the behaviour of the respiratory system. A common approach to detect the respiratory sounds is lung auscultation, however, this method has significant limitations including low sensitivity of human ear or ambient background noise. This article targets the major limitations of lung auscultation and presents a new approach to analyse the respiratory sounds and visualise them together with the respiratory phases. The respiratory sounds from 41 patients were recorded and filtered to eliminate the ambient noise and noise artefacts. The filtered signal is processed to identify the respiratory phases. The article also contains an approach for removing the noise that is very difficult to filter but the removal is crucial for identifying the respiratory phases. Finally, the respiratory phases are overlaid with the frequency spectrum which simplifies the orientation in the recording and additionally offers the information on the inter-individual ratio of the inhalation and exhalation phases. Such interpretation provides a powerful tool for further analysis of lung sounds, simplifythe diagnosis of various types of respiratory tract dysfunctions, and returns data which are comparable among the patients.